WO2009131185A1 - Device for measuring viscosity/elasticity and method for measuring viscosity/elasticity - Google Patents

Abstract

A device for measuring viscosity/elasticity is characterized in that the device comprises a conductive rotor, a container containing an object sample for detecting viscosity in which the rotor is arranged, magnets arranged around the container and applying a magnetic field to the rotor, a rotation control section for applying a rotating magnetic field to the rotor by driving the magnets to induce an induction current in the rotor, and rotating the rotor by applying a rotary torque thereto through Lorentz interaction of the induction current and the magnetic field applied to the rotor, a rotation detection section for detecting the number of revolutions of the rotor, and a dynamical characteristics detection section for detecting the viscosity and/or elasticity of the sample touching the rotor from the number of revolutions.

Description

Viscosity / elasticity measuring apparatus and viscosity / elasticity measuring method

The present invention relates to a viscosity / elasticity measuring apparatus and a viscosity / elasticity measuring method for measuring viscosity and elasticity which are mechanical properties of a substance.
This application claims priority based on Japanese Patent Application No. 2008-116359 filed in Japan on April 25, 2008, the contents of which are incorporated herein by reference.

Viscosity and elasticity of substances are measured in the manufacturing process of pharmaceuticals, foods, paints, inks, cosmetics, chemical products, paper, adhesives, fibers, plastics, beverages (eg beer), detergents, concrete admixtures, silicon, etc. It is an indispensable measurement technology for management, performance evaluation, raw material management, and research and development. Therefore, conventionally, measurement of viscosity and elasticity has been performed in order to detect the mechanical properties of the target substance (see, for example, Patent Document 1).

Conventionally known methods for measuring viscosity include the following methods.
(1) In the viscosity tube method, the viscosity of the fluid is measured from the speed at which the fluid flows through the narrow tube.
(2) A method in which a vibrator is brought into contact with a sample and viscosity is measured by a change in amplitude.
(3) A method for measuring viscosity from the propagation characteristics of surface acoustic waves.
(4) A method of measuring viscosity by directly measuring a torque generated by viscous resistance by rotating a rotor in a sample.
(5) A method of measuring the viscosity from the falling time of the hard sphere falling in the fluid sample.
(6) In the dynamic light scattering method, viscosity is obtained from a diffusion coefficient obtained by irradiating a laser beam to a Brownian moving particle and measuring dynamic scattering.
(7) In the Zimm type viscosity measurement method, a probe suspended in a sample is rotated, and the viscosity is measured from the rotational torque.

JP 2005-69872 A

However, among the above-described methods for measuring viscosity, the methods described in (1) to (5) have a drawback that a large amount of sample of several cc or more is required for measuring viscosity.
In the methods described in (2) to (5), the sample needs to have a viscosity of at least 10 cP in order to accurately measure the viscosity. Therefore, these methods have a drawback that the viscosity of a low-viscosity material cannot be measured.
Furthermore, the method (6) has a drawback that the measuring apparatus becomes large, and there is a difficulty that it cannot be applied to other than the transparent sample.

In addition, the method described in (7) has a disadvantage that the probe floated on the surface by buoyancy is rotated, causing ripples on the sample surface, and energy loss for this cannot be ignored. Further, when a molecular adsorption film is formed on the surface of the sample, there is a drawback that a measurement error occurs due to the surface viscoelasticity of the film. Since the rotation of the probe depends on the length of the portion submerged in the fluid sample, there is a restriction that the density of the sample material needs to be known.
In any of the methods described in (1) to (7), the sample container is expensive and the container needs to be reused. For this reason, it is necessary to clean the sample container after the measurement. If the previous measurement sample is not completely removed, the influence remains and there is a restriction that high-precision measurement cannot be performed.

That is, the viscoelasticity measuring methods generally used until now have a drawback that a certain amount of sample is required in order to obtain a certain measurement accuracy.
In addition, there is a drawback that measurement accuracy is deteriorated for a substance having a viscosity of less than 100 cP. In addition, the rotational viscometer and the measurement by light scattering have a restriction that the apparatus becomes large and simple measurement cannot be performed.
For the reasons described above, it has been difficult to easily measure a small amount of sample with respect to viscosity and elasticity, which are universal physical quantities for liquids and other soft materials, by the method based on the conventional principle. In addition, it was difficult to measure viscosity and elasticity of a low viscosity sample with high accuracy. In addition, there were restrictions on measurement efficiency, such as the need to clean the measurement container.

The present invention has been made in view of such circumstances. Compared to conventional measurement methods, the present invention can measure viscosity and elasticity with a relatively small amount of sample, is a small and simple measuring device, and detects a substance to be detected. It is an object of the present invention to provide a viscosity / elasticity measuring apparatus and a viscosity / elasticity measuring method that can be disposed of at low cost.

The viscosity / elasticity measuring apparatus (mechanical characteristic measuring apparatus) of the present invention stores a conductive rotor, a sample (a detection symmetric material for detecting viscosity and / or elasticity) and the rotor, and the sample is contained in the sample. A container in which the rotor is disposed, a magnet disposed around the container, for applying a magnetic field to the rotor, and driving the magnet to apply a rotating magnetic field to the rotor; A rotation control unit that induces an induced current and applies a rotational torque to the rotor to rotate by Lorentz interaction between the induced current and a magnetic field applied to the rotor, and detects a rotational motion of the rotor Viscosity / elasticity comprising: a rotation detection unit; and a dynamic characteristic detection unit (viscosity / elasticity detection unit) for detecting the viscosity / elasticity of the sample in contact with the rotor based on the rotational torque and the rotational motion It is a measuring device.
The viscosity detected in the above apparatus may be indicated by the viscosity coefficient of the sample.
The elasticity detected in the device may be indicated by an elastic modulus.

In the viscosity / elasticity measuring apparatus, the rotation detection unit detects the rotation number of the rotor, and the mechanical property detection unit detects the viscosity of the sample based on the rotation torque and rotation number of the rotor. -It may be an elasticity measuring device.
In the viscosity / elasticity measuring apparatus, the rotation detection unit is configured to move from an initial stationary position before the rotational torque is applied to an equilibrium stationary position where the rotor is stationary due to a balance between the rotational torque and the elastic resistance of the sample. It may be a viscosity / elasticity measuring device that detects a rotation angle and detects the elasticity of the sample based on the rotation torque and rotation angle of the rotor.

The viscosity / elasticity measuring apparatus further includes a storage unit for storing standard data obtained by measuring in advance a relationship between the rotational torque of the rotor and the rotational speed in a plurality of substances (standard samples) having a known viscosity. A viscosity / elasticity measuring device that detects the viscosity of the sample by comparing the standard data with the relationship between the rotational torque and the rotational speed of the rotor in the sample measured by the mechanical property detection unit. There may be.
The viscosity / elasticity measuring apparatus further includes a storage unit for storing standard data in which a relationship between a rotational torque and a rotational angle of the rotor in a plurality of substances having known elasticity is measured in advance, and the mechanical characteristics It may be a viscosity / elasticity measuring device that detects the elasticity of the sample by comparing the relationship between the rotation torque and the rotation angle of the rotor in the sample measured by the detection unit and the standard data. .

The viscosity / elasticity measuring apparatus is a viscosity / elasticity measuring apparatus in which a mark is added to the rotor, and the rotation detecting unit detects the rotation of the rotor by detecting the rotation of the mark. Also good.
In the viscosity / elasticity measuring device, at least a part of the bottom of the rotor is in contact with the bottom of the inner surface of the container, and the bottom of the inner surface of the container in contact with the rotor is a smooth flat surface or a smooth concave curved surface. In addition, the viscosity / elasticity measuring apparatus may be characterized in that the bottom of the rotor is a smooth convex curved surface.

The viscosity / elasticity measuring device may be a viscosity / elasticity measuring device in which the radius of the rotor is determined by the following equation.

Where R is the radius of the rotor, g is the acceleration of gravity, ω is the angular velocity, η is the viscosity coefficient, Δρ is the density difference between the rotor and the sample, μ is the friction coefficient between the lower part of the rotor and the bottom of the container, and α and β are It is a coefficient.
Here, the viscosity coefficient η may be a condition of R by applying a viscosity coefficient of a substance having a known viscosity similar to the sample (for example, a substance having substantially the same or chemical composition as the sample). . Alternatively, a value slightly higher than the viscosity coefficient of a substance having a known viscosity similar to the sample (about 110 to 150%) may be set as a temporary viscosity coefficient, and R may be obtained by applying the above equation. .

The viscosity / elasticity measuring apparatus may be a viscosity / elasticity measuring apparatus in which the rotor is partially or entirely submerged in the sample.
The viscosity / elasticity measuring apparatus may be a viscosity / elasticity measuring apparatus in which the sample is a liquid or a soft material.

In the viscosity / elasticity detection method of the present invention, the process of filling a container with a sample (substance to be detected) whose viscosity / elasticity is to be detected, placing a conductive rotor in the sample, and surrounding the container A process of applying a magnetic field to the rotor by an arranged magnet, and temporally changing the magnetic field, inducing an induced current in the rotor, and applying the induced current to the rotor Based on Lorentz interaction with a magnetic field, a rotation control process for applying rotation torque to the rotor for rotation, a rotation detection process for detecting the rotation movement of the rotor, the rotation torque and the rotation movement, and the rotor And a mechanical property detection process for detecting the viscosity and elasticity of a sample in contact with the sample.
The viscosity detected in the above method may be indicated by the viscosity coefficient of the sample.
The elasticity detected in the above method may be indicated by an elastic modulus.

The viscosity / elasticity measuring method includes rotating the rotor in the rotation control process, detecting the rotation speed of the rotor in the rotation detection process, and determining the viscosity of the sample based on the rotation torque and the rotation speed. Viscosity / elasticity measuring method may be used.
In the rotation control process, the viscosity / elasticity measuring method is an equilibrium stationary position where the rotor is stationary by the balance between elastic resistance and the torque from the initial stationary position before the torque is applied by the rotational torque. The rotor is rotated until the rotation angle from the initial stationary position to the equilibrium stationary position is detected in the rotation detection process, and in the mechanical characteristic detection process, the rotor is moved based on the rotation torque and the rotation angle. It may be a viscosity / elasticity measuring method for detecting the elasticity of the sample in contact.

The viscosity / elasticity measuring method further includes a step of preparing standard data by measuring in advance the relationship between the rotational torque of the rotor and the rotational speed in a plurality of substances (standard samples) having a known viscosity. The viscosity / elasticity measuring method for detecting the viscosity of the sample by comparing the relation between the rotational torque of the rotor and the number of rotations in the sample with the standard data.
The viscosity / elasticity measuring method further includes a step of preparing standard data by measuring in advance the relationship between the rotational torque and rotational angle of the rotor in a plurality of substances (standard samples) having known elasticity. The viscosity / elasticity measuring method for detecting the elasticity of the sample by comparing the relationship between the rotational torque and the rotation angle of the rotor in the sample with the standard data may be used.
In the rotation control process of the viscosity / elasticity measuring method, the magnetic field may be controlled to be a rotating magnetic field in which the horizontal direction of the magnetic field (the horizontal component of the magnetic field direction) rotates with time.
In the above viscosity / elasticity measuring method, the rotor may be made of a material having a specific gravity greater than that of the sample.

As described above, according to the present invention, since the viscosity and / or elasticity is measured from the relationship between the rotational torque applied to the rotor rotating in contact with the sample and the rotational motion of the rotor, a small amount of detection object is detected. With this sample, the viscosity over a wide range from low viscosity to high viscosity can be measured. The rotor is rotated by applying a rotating magnetic field to the rotor, the rotation speed of the rotor is measured, the viscosity of the sample is detected from the relationship between the rotation torque and the rotation speed of the rotor, and the rotation torque and the rotor are detected. Since the elasticity of the sample is detected from the relationship with the rotation angle, the viscosity and elasticity can be measured with a simpler apparatus than in the past. Furthermore, the container which puts a sample can utilize a normal test tube etc., and can be made disposable. Therefore, the labor for washing the container is omitted, and the influence of the immediately preceding measurement substance can be completely eliminated, and highly accurate measurement can be performed.

It is a block diagram which shows the structural example of the viscosity and elasticity detection apparatus by embodiment of this invention. It is a graph showing the relationship between the difference between the rotational speed of the rotating magnetic field and the rotational speed of the rotor (sphere) when the detection target substance is water, and the rotational speed (rotational speed) of the rotor. It is a graph showing the relationship between the rotational speed of a rotating magnetic field and the rotational speed of a rotor (sphere) when the detection target substance is sucrose, and the rotational speed (number of rotations) of the rotor.

Hereinafter, a viscosity / elasticity measuring apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration example of a viscosity / elasticity measuring apparatus according to the embodiment.
In this figure, a container 101 is, for example, a small test tube. The container 101 stores a detection target object for measuring viscosity (that is, viscosity coefficient) as a mechanical physical property. The inner diameter of the container 101 only needs to be slightly larger than the diameter of the rotor 106 described below. Further, the depth of the sample (detection target) stored in the container 101 at the time of measurement may be such that the rotor 106 is immersed. For this reason, it is possible to measure with a very small amount of sample. For example, when a 1 mm conductor sphere is used as the rotor 106, it is sufficient that the required amount of sample is 100 μL. Here, the rotor 106 may be partially or entirely submerged in the sample that is the detection target substance.

The rotor 106 is made of a conductor (for example, a metal such as aluminum), and has a shape in which a lower portion in contact with the container 101 has a smooth convex curved surface. For example, the rotor 106 may be spherical or hemispherical (that is, a shape in which a portion in contact with the inner bottom portion of the container 101 (the bottom portion of the container inner surface) has a shape of a part of a spherical surface). The rotor 106 may have a spheroid shape. The rotor 106 is disposed in the container 101 so as to be in contact with the detection target. That is, the rotor 106 is arranged so that part or all of the rotor 106 is immersed in this detection target. The inner bottom portion of the container 101 with which the lower portion of the rotor 106 is in contact may be a smooth flat surface or may have a concave smooth curved surface.
A commercially available metal sphere can be used as the rotor 106. Therefore, by using it together with a commercially available test tube of the container 101, the portion in contact with the sample can be made a disposable configuration. For this reason, there is an advantage that post-treatment such as incineration and sterilization can be easily performed even when a substance that requires special attention for disposal, such as biomaterials, is used as a measurement target.
According to the present invention, it is possible to measure the viscosity and elasticity of a very small amount of sample using a small rotor. For example, the rotor may be a metal sphere having a diameter of 1 cm or less or a diameter of 2 mm or less. According to the present invention, viscosity and elasticity can be measured even with a sample having a volume of about 100 to 500 μl.

Around the container, electromagnets 102, 103, 104, and 105 are arranged.
The set A of the electromagnet 102 and the electromagnet 103 is placed in series in the plane perpendicular to the longitudinal direction of the container 101 with the container 101 interposed therebetween.
The set B of the electromagnet 104 and the electromagnet 105 is placed in series in the same plane as the set B with the container 101 interposed therebetween in a direction orthogonal to the arrangement direction of the set A.
That is, when the longitudinal direction of the container 101 is arranged along the z axis of the orthogonal coordinate system, the set A can be arranged along the x axis and the set B can be arranged along the y axis.
For example, the tension direction of the container 106 may be arranged along the vertical direction, and the electromagnet sets A and B may be arranged in a horizontal plane.

The electromagnets 102, 103, 104, and 105 are connected to the rotation control unit 107. The rotation control unit 107 alternately drives the electromagnets of the set A and the set B, and alternately generates and varies magnetic fields in two directions (x-axis direction and y-axis direction) orthogonal to each other.
For example, when the rotation control unit 107 is driving the electromagnet 102 and the electromagnet 103 of the set A (that is, when a current is passed through the coils of the electromagnet 102 and the electromagnet 103), the electromagnet 104 and the electromagnet of the set B 105 is not driven. When the electromagnet 104 and the electromagnet 105 of the set B are driven, the electromagnet 102 and the electromagnet 103 of the set A are not driven.
The rotation control unit 107 applies a rotating magnetic field to the rotor 106 by the electromagnet control described above, and induces an induced current in the rotor 106. Then, due to the Lorentz interaction between this induced current and the magnetic field applied to the rotor 106, the rotor 106 is rotated by giving a rotational torque.
The dynamic characteristic detection unit 108 instructs the rotation control unit 107 about the time period for alternately driving.

In the above-described configuration, an electromagnet is used, and a rotating magnetic field is applied to the rotor 106 by driving the electromagnet coil by passing a current sequentially. Instead, a pair of permanent magnets are arranged in series via the container 101, and the permanent magnets are rotated around the container 101 by a motor or the like to apply a rotating magnetic field to the rotor 106. Thus, the rotor 106 may be configured to be given rotational torque. At this time, the rotation control unit 107 controls the rotation speed of the set of permanent magnets in response to an instruction from the mechanical characteristic detection unit 108.

The image processing unit 109 includes, for example, an image sensor (CCD) having a microscope. The image processing unit 109 is disposed at the upper part of the opening of the container 101. The image processing unit 109 measures the rotation speed of the rotor 106 by detecting the rotation of the mark added to the rotor 106. Therefore, the image processing unit 109 is arranged above the container 101 so that the imaging direction is a position where a mark added to the upper surface of the rotor 106 can be detected.

The standard data storage unit 110 stores standard data indicating the relationship between the rotational torque applied to the rotor 106 and the rotational speed of the rotor 106 for a plurality of standard samples having different viscosities.
Standard data can be obtained by putting each standard sample in the container 101 in advance, rotating the rotor 106, and recording the rotational torque applied to the rotor 106 and the rotational speed of the rotor 106.
In the measurement of each standard sample, the rotational speed at the rotor 106 is changed, the rotational torque at each rotational speed is calculated, and the slope of the linear curve approximated by the equation (8) described later is obtained as a standard. Set as part of the data.

The mechanical property detection unit 108 is connected to the image processing unit 109 and the standard data storage unit. The dynamic characteristic detection unit 108 acquires data on the rotation speed of the rotor 106 output from the image processing unit 109 and the rotation torque corresponding to the rotation speed. Next, the slope of the linear curve represented by the equation (8) described later is obtained for the detection target substance, and the ratio with the slope of the standard data read from the standard data storage unit 110 is obtained. That is, the slope of the primary curve of the standard data is divided by the slope of the primary curve of the detection target substance, and the viscosity η of the detection target substance is calculated by multiplying the slope of the standard data by the slope ratio.
At this time, the mechanical property detection unit 108 can also determine the viscosity of the detection target substance based on a plurality of standard data. For example, the mechanical property detection unit 108 may read the slopes of the primary curves in a plurality of different standard samples stored in the standard data storage unit 110. In this case, for each standard data, the slope of the primary curve of the standard data is divided by the slope of the primary curve of the substance to be detected, and the viscosity ratio is obtained by multiplying the viscosity of the corresponding standard data by the slope ratio. The viscosity value obtained based on the standard data may be averaged to obtain the viscosity of the detection target substance.

Hereinafter, the theory of measuring the viscosity based on the rotational torque applied to the rotor 106 and the rotational speed of the rotor 106 will be described.
Here, in order to explain based on an orthogonal coordinate system, the longitudinal direction of the container is a direction parallel to the z axis, the arrangement of the set A is a direction parallel to the x axis, and the arrangement of the set B is a direction parallel to the y axis. Yes.
For example, a magnetic field parallel to the x axis is generated around the container 101 by the electromagnets 102 and 103 of the set A as indicated by B = (B 0 cosωt, 0, 0), and the y axis is generated by the electromagnets 104 and 105 of the set B. May be generated as shown by B = (0, B 0 sin ωt, 0). Here, B0 is the maximum value of the magnetic field strength, ω is the angular velocity, and t is time.
The rotor 106, which is a conductor, has a magnetic field B (rotating magnetic field) that changes over time.
rotE =-(dB / dt)
An electric field that satisfies is generated.
This electric field is calculated as in the following equation (1).

Thereby, in the rotor 106, the electrical conductivity of the conductor is σ,
I = σE
Current flows. Due to the Lorentz interaction between the current I and the magnetic field B, the rotor 106 is subjected to a force F (Lorentz force) represented by the following equation (2).

In F above, the radial component around the central axis of the rotor 106 perpendicular to the rotation plane can be calculated by the following equation (3) by integrating over one period of time change.

The force _Fθ expressed by the above equation (3) is a force that rotates the rotor 106 around the vertical central axis of the sphere. The torque T is expressed by the following equation (4).

The rotor 106 is rotated by the torque T. However, there are the following two factors that determine the rotation speed.
One is the friction between the rotor 106 and the bottom of the container 101, and the other is the viscous resistance of the substance to be detected that the rotor 106 contacts.
In order to accurately obtain the viscosity of the detection target substance in contact with the rotor 106 from the rotation of the rotor 106, the resistance due to the frictional force at the bottom of the container 101 is substantially the same as the viscosity resistance of the detection target substance. Must be about (ie, a similar number) or small.

Here, in order to simplify the formula, the radius perpendicular to the rotation surface of the rotor 106 is R, and the effective area in the lower area of the rotor 106 in which the lower part of the rotor 106 is in contact with the bottom of the container 101. Let the radius of the contact surface be αR (a <1).
Within this effective contact radius, the stress due to gravity applied to the rotor 106 is assumed to be constant.
Further, if the friction coefficient between the lower part of the rotor 106 and the bottom of the container 101 is μ, the density difference between the rotor 106 and the detection target substance is Δρ, and the gravitational acceleration is g, the friction is overcome and the ball is overcome. The torque T _f required for rotation can be calculated by the following equation (5).

Further, the torque _Tr required for the rotor 106 to rotate at the angular velocity ω in an infinite space filled with the detection target substance is such that the viscosity coefficient is η and is represented by the following equation (6). is there.

When the lower portion of the rotor 106 is in contact with the flat or curved bottom of the container 101, the required torque _Tf further increases. If this coefficient is β, β is on the order of 1 and is larger than 1. Β includes a coefficient of an indirect interaction between the rotor 106 and the side wall of the container 101 when the detection target substance rotates due to the rotation of the rotor 106. Up to equation (6), β = 1.
From the above, it can be seen that the condition for the viscous resistance to work stronger than the frictional force is T _r > T _f . The torque T _f is proportional to the fourth power of R, and the torque T _r is proportional to the third power of R. Therefore, this condition can be satisfied if a sufficiently small R is selected.
That is, the condition for measuring the viscosity of the liquid having a viscosity coefficient (viscosity) η is determined by the following equation (7).

In many cases, the sample whose viscosity is to be measured is obtained by changing the characteristics of a known substance. Therefore, the viscosity coefficient of a known substance similar to the sample (for example, a substance having a similar chemical composition) or a value of about 110 to 150% is applied to η in the above formula as a temporary viscosity coefficient, and the condition regarding R is obtained. be able to. *

For example, assuming that the target substance is water, η = 10 ⁻³ Pas, an aluminum sphere is assumed as the rotor 106, Δρ˜2000 kg / m ^3, and α˜about 1/100, β˜ If it is about 1 and μ is about 0.1, then R <1 mm is a condition at an angular velocity ω of about 10 rad / s at one rotation per second.
The torque _Tr applied to the aluminum sphere is determined by the rotation speed of the magnetic field (the speed at which the set A and the set B are sequentially driven to change the magnetic field in the x-axis direction or the y-axis direction) and the actual rotation of the aluminum sphere. Proportional to speed difference.

Therefore, the rotational torque T applied to the sphere can be estimated by determining the rotational speed of the magnetic field in advance and measuring the rotational speed of the sphere.
For the calculation of the rotational torque T, the equation (4) may be used, or a calibration curve (inclination of standard data stored in the standard data storage unit 110) obtained using a standard sample with a known viscosity. May be used.
The torque T thus obtained is expressed by the following equation (8).

Thus, the relationship between the applied torque T and the angular velocity ω is a linear curve passing through the intercept. That is, when the angular velocity ω is plotted on the horizontal axis and the torque T is plotted on the vertical axis, the second term of equation (8) can be plotted as an intercept, and a curve passing through one point on the vertical axis. From the intercept (second term in equation (8)), torque due to friction is obtained, and from the slope, viscosity η (first term in equation (8)) is obtained. The angular velocity ω can be obtained from the measured rotational speed.
In the standard data storage unit 110, for a standard sample with a known viscosity, an expression (8) expressed by the relationship between the amount proportional to the rotational torque measured by the viscosity / elasticity detection device and the rotational speed of the rotor 106. ), The slope of the linear curve, that is, the ratio of the change in rotational torque with respect to the rotational speed. These data are stored with a numerical value of viscosity for each of a plurality of standard samples having different viscosities.

For observation of the rotational motion of the rotor 106, the rotational speed of the rotor 106 is measured by detecting the rotational motion of the mark added to the rotor 106 using the imaging device 111 with a microscope in FIG.
The rotation speed may be measured using other methods. For example, the method may be replaced with a method of optically measuring a change in reflection / interference pattern due to rotation by irradiating the rotor 106 with laser light. Alternatively, a part of the rotor 106 is replaced with a dielectric, and a capacitor is configured such that the rotor is sandwiched between the electrodes. From the periodic change in the dielectric constant of the capacitor accompanying the rotation of the rotor 106, A method of measuring the number of rotations of the rotor 106 may be used.

The observation with the image sensor 111 may be replaced with a method in which the container 101 is made of a transparent material and observation is performed from the bottom with an inverted microscope. In this case, the observation can be performed through a very thin layer of the detection target substance between the bottom of the container 101 and the lower part of the rotor 106. Therefore, even if the detection target substance is a substance such as an ink material that hardly transmits light, the measurement can be performed. At this time, a mark for detecting the rotational speed is added to the lower portion of the rotor 106.
The period and direction of the magnetic field applied to the rotor 106 by the rotation control unit 107 described above may be arbitrarily changed.
For example, periodic rotational torque can be applied to the rotor 106 by periodically sweeping the direction and rotational speed of the magnetic field.

In addition to viscosity, the viscosity coefficient is changed from a stationary position when a constant torque is applied to a material that has elasticity such as gel or rubber, or a material such as a polymer solution that generates elasticity due to viscosity relaxation. In addition, the elastic modulus can be determined simultaneously.
Here, the elastic modulus, like the spring constant, exerts a restoring force proportional to the rotational deformation. Therefore, when the sample has elasticity in addition to viscosity, the restoring force due to the elastic modulus increases in proportion to the strain. Therefore, when the rotor 106 is rotated to some extent, the elastic force (elastic resistance) and the torque generated by the magnetic field balance and come to rest.

In other words, the magnitude of the rotating magnetic field generated by the electromagnets 102 to 105 is changed, the magnitude of the rotational torque applied to the rotor 106 is changed by changing the rotation speed, and the equilibrium stationary position of the rotor 106 is measured. Thus, the rotation angle from the initial state where no rotational torque is applied to this stationary position is detected. The rotation angle is proportional to the applied rotational torque, and the proportionality coefficient is inversely proportional to the elastic modulus. The elastic modulus can be obtained from this. At this time, a standard sample having a known elastic modulus is used as in the measurement of the viscosity. From the relationship between the rotational torque and the rotational angle, the proportionality coefficient is obtained for the standard sample. The elastic modulus of the detection target substance can be obtained from the ratio of the proportionality coefficient obtained for the detection target substance (measurement sample) and the proportionality coefficient obtained from the standard sample.

By changing the rotational torque applied to the rotor 106 with time, the elastic modulus and viscosity can be determined simultaneously.
For example, when a constant rotational torque is applied to the rotor 106, the applied magnetic field is erased instantaneously, and the subsequent movement of the rotor 106 is observed, the rotor 106 vibrates due to the elasticity of the sample and vibrates due to the viscosity. The amplitude of is decreasing. It is also possible to determine the elastic modulus and the viscosity from the amplitude, period and duration of the vibration of the rotor 106 in the detection object. For example, the elastic modulus of the detection target substance can be obtained by comparing the amplitude, period and duration of vibration of the rotor 106 in the standard sample with the amplitude, period and duration of vibration of the rotor 106 in the detection target. it can.

Periodic rotational torque can be applied to the rotor 106 by periodically sweeping the direction of the magnetic field and the rotational speed.
By observing the amplitude and phase of the rotational vibration of the rotor 106 while changing this period, it is possible to uniquely determine the viscosity and the elastic modulus.
In this observation, the damped oscillation after erasing the magnetic field is regarded as a frequency spectrum, and both are the same measurement in principle.

<Application example>
Hereinafter, specific application examples according to the present embodiment will be described in more detail. However, the present invention is not limited to the following application examples.
The following viscosity detection processing was performed using the viscosity / elasticity measuring apparatus (mechanical property measuring apparatus) shown in FIG.
A glass test tube having an inner diameter of 7 mm and a height of 30 mm was used as the container 101, and 0.4 cc of pure water at 20 ° C. was inserted as a measurement target sample (detection target substance) into the glass test tube.
The viscosity of this pure water was 1.0 cP, and an aluminum sphere having a diameter of 2 mm was submerged as a rotor 106 in this pure water.

Next, a rotating magnetic field was generated by rotating two permanent magnets around the sample container.
In response to the rotational torque generated by this rotating magnetic field, the image sensor 110 captured the rotation of the aluminum sphere, and this image was recorded on a video tape. Thereafter, the rotational speed of the aluminum sphere was obtained by image processing (image processing unit 109) by a computer. That is, the rotational speed of the aluminum sphere at that time was measured while changing the rotational speed of the rotating magnetic field.

FIG. 2 is a graph showing the relationship between the rotational speed of the rotating magnetic field and the rotational speed of the rotor 106 (a parameter proportional to the rotational torque) and the rotational speed of the aluminum sphere.
As described above, the difference in rotational speed between the magnetic field and the rotating object is proportional to the rotational torque generated in the aluminum sphere.
Therefore, the vertical axis of this graph represents an amount proportional to the torque. This relationship is in the form of a linear function expressed by equation (8). It can be seen that the viscosity is obtained from the slope in the first term, and the frictional force is obtained from the intercept (relative to the vertical axis) indicated by the second term. .

Furthermore, the following operation was performed using the mechanical property measuring apparatus shown in FIG. Specifically, a glass test tube having an inner diameter of 7 mm and a height of 30 mm was used as a sample container, and 0.4 cc of an aqueous solution of sucrose having a weight ratio of 30% was inserted into the test tube. The viscosity of this aqueous solution is 3.2 cP.
As a rotor 106, an aluminum sphere having a diameter of 2 mm was submerged in the aqueous solution, and then two permanent magnets were rotated around the container 101 to generate a rotating magnetic field.
The imaging element 111 captures the rotation of the aluminum sphere in response to the rotational torque generated by this rotating magnetic field, records this image on a video tape, and then calculates the rotational speed by image processing (image processing unit 109) by a computer. Asked. That is, the rotational speed of the aluminum sphere at that time was measured while changing the rotational speed of the rotating magnetic field.

FIG. 3 is a graph showing the relationship between the rotational speed of the rotating magnetic field and the rotational speed of the rotor 106 and the rotational speed of the rotating object.
It can be seen that the slope of the graph is larger because the viscosity of the aqueous sucrose solution is larger than that of the pure water of FIG.
The rotation speed of the rotating magnetic field in this section is about 0.4 rotation / second, and is derived from the equation (7) that gives the rotation speed corresponding to the frictional force when the viscosity is 3 cP and the diameter of the rotating object is 2 mm. The order is almost the same as the value of 1 rotation / second. This shows that the principle of the present invention is effective.

Further, the ratio of the slopes of FIG. 2 and FIG. 3 is 3.26, which is in good agreement with the actual viscosity ratio 3.2, which indicates that a viscosity of about 1 cP can be measured with high accuracy.
Further, from this result, by obtaining the ratio of the gradient between the rotational torque and the rotational speed of the detection target substance and the standard sample, the viscosity of the detection target substance can be estimated by multiplying this ratio by the viscosity of the standard sample. It turns out that it is possible.

According to the present invention, it is possible to measure viscosity and / or elasticity with high accuracy on a very small amount of sample. In that case, a commercially available inexpensive article can be used for the container and the rotor that are in contact with the sample and can be made disposable. Therefore, the cost required for the apparatus can be reduced, and the influence of contamination of other samples can be completely eliminated. In addition, post-processing for discarding the sample can be performed easily and reliably.

Claims (17)

1. A conductive rotor,
   A container that houses the sample and the rotor, and in which the rotor is disposed;
   A magnet disposed around the vessel for applying a magnetic field to the rotor;
   The magnet is driven to apply a rotating magnetic field to the rotor, an induced current is induced in the rotor, and the rotor is rotated by Lorentz interaction between the induced current and a magnetic field applied to the rotor. A rotation control unit that rotates by applying torque;
   A rotation detector for detecting the rotational movement of the rotor;
   A viscosity / elasticity measuring apparatus comprising: a mechanical property detection unit that detects viscosity / elasticity of a sample in contact with the rotor based on the rotational torque and the rotational motion.
2. The rotation detection unit detects the rotation speed of the rotor, and the mechanical property detection unit detects the viscosity of the sample based on the rotation torque and rotation speed of the rotor. The viscosity / elasticity measuring device described.
3. The rotation detection unit detects a rotation angle from an initial stationary position before the torque is applied to an equilibrium stationary position where the rotor is stationary due to a balance between the rotational torque and an elastic resistance of the detection symmetric material, The viscosity / elasticity measuring apparatus according to claim 1, wherein the mechanical property detection unit detects the elasticity of the sample based on a rotational torque and a rotational angle of a rotor.
4. A storage unit for storing standard data obtained by measuring in advance the relationship between the rotational torque of the rotor in a plurality of substances having a known viscosity and the rotational speed;
   The viscosity of the sample is detected by comparing the relationship between the rotation torque and the number of rotations of the rotor in the sample measured by the mechanical property detection unit and the standard data. 2. The viscosity / elasticity measuring apparatus according to 2.
5. A storage unit for storing standard data obtained by measuring in advance the relationship between the rotational torque of the rotor in a plurality of substances having known elasticity and the rotational angle;
   The elasticity of the sample is detected by comparing the relation between the rotation torque and the rotation angle of the rotor in the sample measured by the mechanical characteristic detection unit and the standard data. 3. The viscosity / elasticity measuring apparatus according to 3.
6. A mark is added to the rotor,
   The rotation detecting section by detecting the rotation of the mark, the viscosity and elasticity measuring device according to any one of claims 1 to claim 5, characterized in that for detecting the rotational movement of the rotor.
7. At least a portion of the bottom of the rotor is in contact with the bottom of the inner surface of the container;
   The bottom of the inner surface of the container in contact with the rotor is a smooth flat surface or a smooth concave curved surface,
   The viscosity / elasticity measuring apparatus according to any one of claims 1 to 5, wherein the bottom of the rotor is a smooth convex curved surface.
8. The viscosity / elasticity measuring apparatus according to claim 1, wherein a radius of the rotor is determined by the following equation.
   

   

   Where R is the radius of the rotor, g is the acceleration of gravity, ω is the angular velocity, η is the viscosity coefficient, Δρ is the density difference between the rotor and the sample, μ is the friction coefficient between the lower part of the rotor and the bottom of the container, and α and β are It is a coefficient.
9. The viscosity / elasticity measuring apparatus according to any one of claims 1 to 5, wherein a part or all of the rotor is submerged in the sample.
10. The viscosity / elasticity measuring apparatus according to any one of claims 1 to 5, wherein the sample is a liquid or a soft material.
11. Filling a container with a sample to be detected for viscosity and elasticity, and placing a conductive rotor in the sample; and
    Applying a magnetic field to the rotor by a magnet disposed around the vessel;
    The magnetic field is changed with time, an induced current is induced in the rotor, and a rotational torque is applied to the rotor by Lorentz interaction between the induced current and a magnetic field applied to the rotor. Rotation control process,
    A rotation detection process for detecting the rotational movement of the rotor;
    A viscosity / elasticity measuring method comprising: a mechanical property detection process for detecting the viscosity / elasticity of a sample in contact with the rotor based on the rotational torque and rotational motion.
12. In the rotation control process, the rotor is rotated,
    Detecting the number of rotations of the rotor in the rotation detection process;
    The viscosity / elasticity measuring method according to claim 11, wherein, in the mechanical characteristic detection process, the viscosity of the sample is detected based on the rotational torque and the rotational speed.
13. In the rotation control process, by rotating torque, the rotor is rotated from an initial stationary position before the torque is applied to an equilibrium stationary position where the rotor is stationary by a balance between elastic resistance and the torque,
    Detecting a rotation angle from the initial stationary position to the equilibrium stationary position in the rotation detection process;
    12. The viscosity / elasticity measuring method according to claim 11, wherein, in the mechanical characteristic detection process, the elasticity of the sample is detected based on the rotational torque and the rotational angle.
14. Further comprising the step of preparing standard data by measuring in advance the relationship between the rotational torque of the rotor in a plurality of substances having a known viscosity and the rotational speed,
    13. The viscosity / elasticity according to claim 12, wherein the viscosity of the sample is detected by comparing the relation between the rotational torque and the rotation speed of the rotor in the sample with the standard data. Measuring method.
15. Further comprising the step of preparing standard data by measuring in advance the relationship between the rotational torque of the rotor and the rotational angle in a plurality of substances having known elasticity,
    The viscosity / elasticity according to claim 14, wherein the elasticity of the sample is detected by comparing the relationship between the rotational torque and the rotation angle of the rotor in the sample with the standard data. Measuring method.
16. The viscosity according to any one of claims 11 to 15, wherein, in the rotation control process, the magnetic field is controlled to be a rotating magnetic field whose horizontal direction rotates with time. -Elasticity measurement method.
17. 16. The viscosity / elasticity measuring method according to claim 11, wherein the rotor is made of a material having a specific gravity greater than that of the sample.

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